1. Field of the Invention
The present invention relates to an apparatus and method for testing subscriber lines and equipment, and more particularly to an apparatus and method for testing subscribers lines and equipment being served by telecommunications devices that are linked by an interface.
2. Description of the Related Art
Today""s network systems have increased in size and complexity to serve diverse user needs for telecommunications services. To achieve efficient operations and maintenance of transmission channels in such a circumstance, telecommunication carriers centrally manage maintenance information at their service centers, monitoring alarm signals from transmission equipment deployed over a wide coverage area, as well as receiving complaint calls from customers. If any failure is reported, they should conduct an appropriate test to locate each problem in a prompt and proper manner.
The ITU-T and ETSI, standardization organizations in this technical field, provide universal data communication interface standards known as V series recommendations. Among those recommendations, V5 interface standards define a set of requirements for digital communications between a local exchange (LE) and an access network (AN), where the term xe2x80x9caccess networkxe2x80x9d refers to a sub-network comprising a central terminal (CT) and remote terminals (RT) to allow individual subscribers to make access to a public switched network. V5 standards provide open interface specifications to enable multi-vendor solutions for telecommunications systems, where LE and AN equipment from different vendors can interoperate.
The V5 recommendations actually include two types of interface specifications: V5.1 and V5.2. FIG. 11 schematically shows a system model using the V5.1 interface. This system includes an access network (AN) 300 which comprises a central terminal (CT) 301 and a remote terminal (RT) 302 being interconnected by a fiber optic cable Lo. The access network 300 is connected to a local exchange (LE) 200 via a 2.048 Mbps digital trunk L1 that conforms to the V5.1 interface standards. In addition to analog telephone equipment, ISDN-BRA digital data terminals are coupled to the remote terminal 302. Here, xe2x80x9cISDN-BRAxe2x80x9d refers to 2B+D basic rate access services of ISDN. The V5.1 interface supports only one 2.048 Mbps digital trunk L1, which permits, for example, 30 channels of 64 kbps digital telephone lines to be connected to the RT 302. Accordingly, two 2.048 Mbps links would be required to accommodate 60 channels.
In contrast to FIG. 11, FIG. 12 schematically shows a system model using the V5.2 interface. This system includes an access network (AN) 300, which comprises a central terminal (CT) 301 and a remote terminal (RT) 302 interconnected by a fiber optic cable Lo. The central terminal 301 is connected to a local exchange (LE) 200 via a 2.048 Mbps digital trunk L2 that conforms to the V5.2 interface standards. The remote terminal 302 serves analog telephone equipment and digital data terminals for ISDN-BRA and ISDN-PRA services. Note that xe2x80x9cISDN-PRAxe2x80x9d stands for 23B+D or 24B/D primary rate access of ISDN.
Compared with the V5.1-based system of FIG. 11, this V5.2-based system has two major differences. First, a line concentrator 302a is incorporated in the RT 302. Second, it is possible to have two or more 2.048 kbps digital trunks to connect between the central terminal 301 and local exchange 200. (Actually, it has at least two trunks L2 for dual redundancy capabilities; one for active channels and the other for protection channels.)
Referring back to FIG. 11, suppose, for example, that the RT 302 has to handle 120 channels of 64 kbps digital terminals. This does not necessarily means that four 2.048 Mbps digital trunks L1 are required, since it is unlikely that all the available digital terminals use connection services at the same time. In reality, average traffic is expected to be much lower than the theoretical peak bandwidth that the remote terminal 302 may require to handle 120, 64 kbps channels. If the assessment of traffic does not necessitate the use of V5.1 interface, the V5.2 interface with line concentration capabilities would be the right choice, since it does not pre-assign the bearer channels to subscribers and thus provides more economical solutions.
While defining physical, electrical, and procedural requirements for digital interface, the V5 recommendations lack the specification of subscriber test methods. Suppose, for example, that a maintenance person stationed at the local exchange 200 is attempting to probe a particular subscriber terminal that is connected to the access network 300. The V5 digital link L1 or L2, however, does not allow him/her to send necessary test parameters to the terminal, because of the lack of specifications for testing telecommunications equipment over a V5 interface. Conventionally, he/she has to use two separate test stations to run a subscriber test, connecting one to the local exchange 200 and the other to the central terminal 301.
FIG. 13 shows a typical configuration of a conventional subscriber test system for V5 interface. In this system, two subscriber test stations 100 and 101 are coupled to a local exchange (LE) 200 and a central terminal (CT) 301, respectively. Besides terminating and switching circuits and trunks, the local exchange 200 directly serves its local subscriber terminals, which will be referred to herein as xe2x80x9cLE-side subscribers.xe2x80x9d The first test station 100 is thus called the xe2x80x9cLE-side subscriber test station.xe2x80x9d
On the other hand, the central terminal 301, as part of an access network (AN) 300, handles calls to/from subscriber terminals connected to a remote terminal (RT) 302 shown in the bottom of FIG. 13. Those terminals will be referred to herein as xe2x80x9cAN-side subscribers,xe2x80x9d and the second test station 101 is thus called the xe2x80x9cAN-side subscriber test station.xe2x80x9d The local exchange 200 and central terminal 301 are interconnected by a 2.048 Mbps digital trunk L that is compatible with the V5 interface specifications. The central terminal 301 is linked to a remote terminal 302 via a fiber optic cable Lo.
Being unable to use the V5 digital link L for testing purposes, as mentioned earlier, the conventional subscriber test system performs a test by using both the LE-side subscriber test station 100 and AN-side subscriber test station 101 simultaneously to probe an LE-side subscriber under test and an AN-side subscriber under test, respectively. One disadvantage of such a conventional subscriber test system is that the maintenance person has to use different test stations to manipulate both the LE-side and AN-side subscriber terminals. This work environment imposes heavier loads on the maintenance person and spoils the efficiency of his/her tasks. Another disadvantage is that the information regarding individual subscribers is not centrally managed, but distributed in separate databases in the local exchange 200 and access network 300. It is therefore difficult to ensure consistency between the two databases because they could be updated separately. Possible data inconsistency could cause inappropriate behavior of the test system, such as testing an incorrect target subscriber, resulting in degraded quality of customer services.
Taking the above into consideration, an object of the present invention is to provide a subscriber test apparatus which provides improved efficiency and quality in maintenance work.
To accomplish the above object, according to the present invention, there is provided an apparatus for conducting a subscriber test for subscribers connected to such telecommunications devices that are linked by an interface. This apparatus comprises: (a) a subscriber test controller which controls a process of a subscriber test by sending related test parameters and identification data to be used to identify a target subscriber to be tested, and (b) a subscriber data controller which controls data concerning the subscribers. The subscriber data controller comprises: (b1) a subscriber data management unit which collects subscriber data and centrally manages the collected subscriber data, and (b2) a target subscriber determination unit, responsive to the identification data sent from the subscriber test control unit, which identifies the target subscriber by using the received identification data in searching the subscriber data being managed by the subscriber data management unit. The apparatus reaches one of the telecommunications devices through a transmission path that is routed separately from links interconnecting the telecommunications devices. The apparatus further comprises (c) a subscriber test execution unit, disposed in the one of the telecommunications devices, which receives the test parameters through the transmission path and runs the subscriber test according to the received test parameters.
Another object of the present invention is to provide a subscriber test method which provides improved efficiency and quality in maintenance work.
To accomplish the above object, according to the present invention, there is provided a method of conducting a subscriber test for subscribers connected to such telecommunications devices that are linked by an interface. This method comprises the following steps: (a) collecting subscriber data and centrally managing the collected subscriber data; (b) sending identification data to identify a target subscriber to be tested; (c) identifying the target subscriber by using the received identification data in searching the subscriber data; (d) sending test parameters relating to the subscriber test through a transmission path that is routed separately from links interconnecting the telecommunications devices; and (e) running the subscriber test for the determined target subscriber, according to the received test parameters.
The above and other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.